8M0251124 Maintenance Kit for Mercury 25HP 30HP | JLM Marine

8M0251124 Maintenance Kit for Mercury 25HP 30HP | JLM Marine

This comprehensive maintenance kit is engineered for Mercury 25HP and 30HP Japanese model outboards, delivering all essential components for a complete service interval in one package. Designed to restore and maintain peak engine performance, this kit simplifies routine maintenance and ensures reliable operation on the water.

This kit directly replaces OEM part number 8M0251124, providing an aftermarket solution that meets factory specifications. It includes the water pump rebuild components, thermostat assembly, fuel filter, drain gaskets, and gear oil pump—everything needed for a thorough maintenance service.

• Complete service kit with 14 components including water pump parts, thermostat, fuel filter, and gear oil pump
• Fits Mercury 25HP and 30HP Japanese models
• Direct replacement for OEM part number 8M0251124

Part Number Cross-Reference

Use this table to confirm equivalent part numbers across OEM and aftermarket brands.

Compatible Engine Models

Confirm your engine model/year in the table below. For Mercury owners, here's a guide to help you identify your engine's serial/model: Mercury Serial Number Guide. You can also review exploded diagrams to verify part numbers: Mercury Parts Diagrams & Catalog.

Technical Specifications

Package Contents

This maintenance kit includes the following components:

• 161572 - Insert Cup × 1
• 47-16154-1 - Impeller × 1
• 27-161602 - Gasket × 1
• 161592 - Plate × 1
• 27-161582 - Gasket × 1
• 28-161551 - Key × 1
• 910103-5652 - Screw × 4
• 8M0119207 - Thermostat × 1
• 27-853702005 - Thermostat Gasket × 1
• 35-8M0088825 - Fuel Filter × 1
• 8M02046936 - Drain Gasket × 2
• 8150264 - Cotter Pin × 1
• 27-828816 - Oil Drain Screw Gasket × 1
• 24OP149 - Gear Oil Pump × 1

Installation Guide

1. Disconnect the battery and ensure the engine is cool before beginning work. Gather all tools and components from the kit.
2. Remove the lower unit from the outboard following your engine's service manual. Drain the gear oil completely and inspect for metal particles or contamination.
3. Remove the water pump housing cover and extract the old impeller, plate, and insert cup. Clean all surfaces thoroughly, removing old gasket material and debris.
4. Install the new insert cup (161572) into the pump housing, ensuring it seats properly. Place the new impeller (47-16154-1) with blades oriented in the correct rotation direction.
5. Insert the key (28-161551) into the driveshaft slot, then position the new plate (161592) over the impeller. Apply a thin layer of marine grease to the impeller blades for easier installation.
6. Install the new gaskets (27-161602 and 27-161582) on their respective surfaces. Reattach the pump housing cover using the four new screws (910103-5652), tightening in a cross pattern.
7. Remove the old thermostat from the powerhead and clean the seating area. Install the new thermostat (8M0119207) with the new gasket (27-853702005), ensuring correct orientation.
8. Replace the fuel filter (35-8M0088825) on the fuel line, ensuring proper flow direction as marked on the filter body. Tighten connections securely to prevent leaks.
9. Install the new drain gaskets (8M02046936) on the lower unit drain and vent plugs. Replace the oil drain screw gasket (27-828816) as needed.
10. Reattach the lower unit to the outboard, aligning the driveshaft and water tube carefully. Secure all mounting bolts to factory torque specifications.
11. Using the included gear oil pump (24OP149), refill the lower unit with the manufacturer-recommended gear oil until it flows from the vent hole. Install the vent plug first, then the drain plug with the cotter pin (8150264).
12. Reconnect the battery and perform a water test with the engine in a test tank or on muffs. Check for proper water flow from the telltale and inspect all connections for leaks.

Troubleshooting & FAQ

Q: How do I confirm this kit fits my Mercury engine?
A: This kit is designed specifically for Mercury 25HP and 30HP Japanese models. Verify your engine's model designation and check that your current part number is 8M0251124. If you're unsure, consult your engine's service manual or use the Mercury serial number guide linked above to identify your exact model.

Q: How often should I replace these maintenance components?
A: Mercury recommends servicing the water pump impeller annually or every 100 hours of operation, whichever comes first. The thermostat and fuel filter should be inspected during this service and replaced if showing wear. Gear oil should be changed at least once per season or every 100 hours.

Q: What are the signs that my water pump impeller needs replacement?
A: Common symptoms include reduced water flow from the telltale, engine overheating, steam from the powerhead, or weak stream during operation. If you notice any of these signs, inspect and replace the impeller immediately to prevent engine damage.

Q: Can I install this kit myself or do I need a professional?
A: If you have mechanical experience and the proper tools, you can install this kit following your engine's service manual. The water pump and thermostat replacement require removing the lower unit, which demands careful alignment during reassembly. Professional installation is recommended if you're unfamiliar with outboard servicing.

Q: OEM vs. Aftermarket?
A: This listing is an aftermarket replacement part (not an OEM component). We build to OEM specifications using comparable-grade materials. Production is done in an ISO9002-certified facility, and each batch is inspected for consistent performance.

Q: How fast do you ship and how much does it cost?
A: We offer fast global shipping—typically 5–15 days worldwide—and standard shipping is free. Expedited options are available at checkout depending on your location.

Q: What is your warranty and return policy?
A: This product includes a 1-year warranty against manufacturing defects under normal use. If something goes wrong, contact our support team with your order details. Returns are accepted within our standard return window (unused & in original condition); please see our policy page or reach out for instructions.

Important Notes

• Verify that the product images and specifications match your original part. If discrepancies exist—even if your model is listed—do not proceed with the purchase.
• This product is an aftermarket replacement part and is not an OEM component.
• Professional installation is recommended to ensure safety and optimal performance.

Why Choose JLM MARINE?

• Quality Assured: As a trusted manufacturer for over 20 years, we supply top marine brands globally.
• Fast Global Shipping: Free delivery worldwide in 5–15 days.
• Direct from Manufacturer: Competitive pricing without compromising quality.